Exploring Filters

While working on some experiments on synthesis, I’ve come to learn that a lot of a good synth’s power lay within its filters for shaping the overall sound.  While looking at my own filter design in Csound (and I don’t call it necessarily “mine” as in “I wrote it”, just as in the sense that it is mine because I’m using it . . . I can’t remember where I pulled the code from), I find it works well to suit what I need it for.  I would, however, like to learn a little bit more about the internals of filter design and how it shapes the tone, so I can be more intentional about how I want a synthesized tone to sound.

;-12dB cutoff
aout1     butterlp     amix1, ifrq+<cutoff1>
aout2    butterlp    amix2, ifrq+<cutoff1>

;bandpass -6dB cutoff for resonance
ares1    butterbp     aout1, ifrq+<cutoff1>, ifrq+<cutoff1>*<bw>
ares2     butterbp     aout2, ifrq+<cutoff1>, ifrq+<cutoff1>*<bw>
ares1     balance     ares1, aout1
ares2     balance     ares2, aout2

Part of my research involves actually listening to filters at work.  I found this nice example of the Moog Ladder Filter below, in which the filter is used to filter the unique aspects of instruments in a song, making the tones really jump out of the song:

In a way, I am reminded of using my Carvin Quad-X guitar preamp as a tube preamp for vocals, which I find really make the mids in vocals really stand out and sound really crisp.  I was using the tubes in the preamp as a filter!  Not only that, but I was using other aspects of the preamp as a unified vocal filter.  With that in mind, it gives me a foundation of what to keep in mind as I research:  the filters are to shape the tone, so a quality filter will help in shaping a quality tone.

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